A pheromone trap is a type of insect trap that uses pheromones to lure insects. Sex pheromones and aggregating pheromones are the most common types used. A pheromone-impregnated lure, as the red rubber septa in the picture, is encased in a conventional trap such as a Delta trap, water-pan trap, or funnel trap.
Pheromone traps are very sensitive, meaning they attract insects present at very low densities. They are often used to detect presence of exotic pests, or for sampling, monitoring, or to determine the first appearance of a pest in an area. They can be used for legal control, and are used to monitor the success of the Boll Weevil Eradication Program and the spread of the gypsy moth. The fact that pheromone traps are highly species-specific can also be an advantage, and they tend to be inexpensive and easy to implement.
However, it is impractical in most cases to completely remove or "trap out" pests using a pheromone trap. Some pheromone-based pest control methods have been successful, usually those designed to protect enclosed areas such as households or storage facilities. There has also been some success in mating disruption. In one form of mating disruption, males are attracted to a powder containing female attractant pheromones. The pheromones stick to the males' bodies, and when they fly off, the pheromones make them attractive to other males. It is hoped that if enough males chase other males instead of females, egg-laying will be severely impeded.
Some difficulties surrounding pheromone traps include sensitivity to bad weather, their ability to attract pests from neighboring areas, and the fact that they generally only attract adults although it is the juveniles in many species that are pests. They are also generally limited to one sex.
Though certainly not all insect pheromones have been discovered, many are known and many more are discovered every year. Some sites curate large lists of insect pheromones. Pheromones are frequently used to monitor and control lepidopteran and coleopteran species, with many available commercially. Some insects for which pheromones are available include: